Incorrect timezone when adding to calendar

Hi there, I have a date and time in the America/Halifax timezone (+0400). My computer is using the America/Halifax timezone. Events are created without any timezone override, but when I add them to calendar via the links, I get the time in America/Halifax PLUS 4 hours.

So if an event is set for 10pm, the add to cal link adds it as 2am. Both Apple and Google (can't test Outlook).

The content of the .ics file is:

BEGIN:VCALENDAR
PRODID:My Website
BEGIN:VTIMEZONE
TZID:America/Halifax
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0400
END:STANDARD
END:VTIMEZONE
VERSION:2.0
BEGIN:VEVENT
UID:4750bf95-e4ad-4f33-bea4-3c5a2c96407c
SUMMARY:Test event 1
DTSTAMP:20241203T165700Z
DTSTART;TZID=America/Halifax:20241218T000000
DTEND;TZID=America/Halifax:20241218T000000
END:VEVENT
END:VCALENDAR

Anything stand out as obviously wrong? Thanks!